The present invention relates to an automatic can changing device for spinning preparation machines, preferable for drawing frames and carding and combing machines, comprising a plurality of conveyor carriages for transporting full and empty cans. The machines preferably comprise at least one fiber lap delivery station for fiber laps which are to be fed into cans and the empty cans are adapted to be moved automatically from the conveyor carriage to a corresponding fiber lap delivery station and the filled cans are also adapted to be moved automatically onto the conveyor carriages.
In the case of a known device of this type (German AS 1 266 672) the empty cans are supplied to the fiber lap delivery station in one direction and the filled cans are removed in the same direction on the other side. Moreover, each carriage is designed to hold two rows of cans: the cans contained in one row of a carriage holding empty cans are first pushed down in succession from the carriage according to the can changing rhythm. The carriage is then moved at right angles to the ejection direction and the cans in the other row are then successively pushed down from the carriage. Likewise, when the filled cans are being loaded onto the carriage, one row of cans is first pushed onto the carriage. The carriage is then moved at right angles to its starting position and the cans in the other row are successively pushed onto the carriage. This system necessitates, among other things, complicated drive mechanisms for the carriages. The empty cans must also first be pushed under the drawing frame connected in series with the fiber lap delivery station and, as a result, the spinning preparation machines must be specially constructed. Tracks for the carriages also extend along three sides of the spinning preparation machines.